MONDAY, Aug. 3, 2015 (HealthDay News) -- Heart attacks take more years from the expected life spans of women and blacks than from white males, a new study suggests.

On average, women lost 10.5 percent more of their expected life than men did, while blacks lost 6 percent more than whites, the study revealed.

Why the gap? Differences in care may be account for some of the disparity, but not all.

"Black patients had more risk factors, were sicker when they first presented to care, and received less treatment than white patients," said study lead author Dr. Emily Bucholz, a pediatric resident at Boston Children's Hospital. "However, we were not able to explain the sex differences in life years lost that we observed."

For the study, the researchers analyzed almost 147,000 Medicare patients who'd been hospitalized for a heart attack from 1994 to 1995. Forty-eight percent of the group was female and 6 percent were black. Their average age when the study began was 74 to 77, according to the study.

After 17 years of follow-up, the researchers found that over 7 percent were still alive. The survival rates were 8.3 percent for white men, 6.4 percent for white women, 5.4 percent for black men and 5.8 percent for black women.

On average, women lost almost two more years of potential life after a heart attack than men across all ages. And blacks lost nearly a year more of potential life after a heart attack compared to whites, the researchers noted.

What's going on? After the researchers adjusted their statistics so they wouldn't be thrown off by factors like the level of illness in the patients, blacks actually gained a life span advantage over whites. This suggests that blacks were sicker when they went to the hospital and weren't treated the same as whites, Bucholz said.

Dr. Jack Tu, a senior scientist at Sunnybrook Health Sciences Center in Toronto, and author of a commentary accompanying the study, said it's "disconcerting" that the findings suggest whites and blacks were treated differently in the hospital, with blacks getting fewer treatments such as clot-busting drugs, bypass surgery and angioplasty.

Still, he said, the study is based on treatments of patients two decades ago. "There are other data showing that the racial differences in treatment have been reduced since that time," Tu said.

As for women, they still lost 8 percent more of their expected life span compared to men even after statistics were adjusted. Researchers aren't sure why this difference exists. Biological differences might be one reason, Bucholz said, or women could be getting worse follow-up care after a heart attack.

What should happen now? "Presumably, more equitable delivery of care both before and after heart attack can help address many of the racial differences in life expectancy and years of life lost after heart attack we observed," she said. To that end, she said, national policymakers need to focus on "reducing racial disparities in health care, but also on understanding why women are at higher risk after heart attack than men."

The study appears in the Aug. 11 issue of the Journal of the American College of Cardiology.